A transmission comprises an input shaft, an output shaft and a speed-change transmission with a plurality of gears which can be engaged alternatively to transmit torque between the shafts. Each gear is associated with a clutch so that the disengagement of a first gear and the engagement of another gear can overlap in time. Consequently, the gearshift can take place without interrupting the torque transmitted, and this is referred to as a gearshift free from traction force interruption.
The actuations of the clutches involved in a gearshift must be matched precisely with one another in order to influence the torque transmitted during the shift as uniformly as possible and so as not to overload any element of the transmission. For example, the clutches can be actuated gradually by hydraulic or mechanical means in order to control slip in the clutch. For example, during the transition from a non-actuated to a fully actuated condition an actuation trajectory for the clutch can be determined, which indicates the degree of its actuation over a predetermined time interval. Such an actuation trajectory is usually determined once and for all either empirically or on the basis of simple assumptions, and then used unchanged thereafter. For the determination, safety margins are usually allowed, for example in order to take into account the influence of temperature, wear or a measurement error. Thus, the precision or efficiency of a transmission control system based on this can be limited.
DE 10 2011 075 913 A1 proposes that the actuation trajectories should be determined on the basis of operating condition parameters of the transmission.